The present invention relates to a video monitoring system and, more particularly, to a video monitoring system of the type detecting the movement of a subject out of a video signal and outputting data representative of the movement.
A video monitoring system of the type described is taught in, e.g., Japanese Patent Laid-Open Publication No. 4-260979. The conventional video monitoring system is used to track moving objects appearing on a screen by executing processing within a preselected period of time without regard to the number of the objects, or to track a particular moving object without being effected by the collision of the object with another moving object or the disappearance of the object due to another object. With this system, it is possible to monitor, e.g., a suspicious person.
The conventional video monitoring system, however, needs a large capacity memory and several LSIs (Large Scale Integrated circuits) and relies on the learning effect of neural networks. Therefore, the system, including an image pick-up device, is extremely expensive. Moreover, the system needs a broad space for installation.
Technologies relating to the present invention are also disclosed in, e.g., Japanese Patent Laid-Open Publication Nos. 63-296132, 6-6659, and 8-249050.
It is therefore an object of the present invention to provide a video monitoring system which, including an image pick-up device, is low cost.
It is another object of the present invention to provide a space saving video monitoring system.
A video monitoring system of the present invention includes an image pick-up device for shooting a subject and outputting a video signal representative of the subject. A processing unit divides the video signal input thereto into a number of blocks frame by frame, calculates mean values of luminance data or color data block by block, calculates differences between the mean values of the blocks of the current frame and the mean values of the corresponding blocks of a frame occurred several frames before, compares values derived from the differences and a mean value of the differences with a preselected value to thereby determine whether or not a movement has occurred, and outputs movement detection data when a movement occurs. A display unit displays the image of the subject and movement detection data. With this configuration, the system is capable of detecting the movement of an image without resorting to any neutral network.